Variational quantum simulation for periodic materials

We present a quantum-classical hybrid algorithm that simulates electronic structures of periodic systems such as ground states and quasiparticle band structures. By extending the unitary coupled cluster (UCC) theory to describe crystals in arbitrary dimensions, for hydrogen chain, we numerically demonstrate UCC ansatz implemented on quantum circuit can be successfully optimized with small deviation from exact diagonalization over entire range potential energy curves. Furthermore, by using subspace expansion method, which truncate Hilbert space within linear response regime state, structure is computed charged excited states. Our work establishes powerful interface between rapidly developing technology modern material science.